Theophilus informs Jerome that he has expelled the Origenists from the monasteries of Nitria, and urges him to show his zeal for the faith by writing against the prevalent heresy. The date of the letter is 400 A.D.

Theophilus, bishop, to the well-beloved and most loving brother, the presbyter Jerome. The reverend bishop Agatho with the well-beloved deacon Athanasius is accredited to you with tidings relating to the church. When you learn their import I feel no doubt but that you will approve my resolution and will exult in the church's victory. For we have cut down with the prophet's sickle Joel 3:13 certain wicked fanatics who were eager to sow broadcast in the monasteries of Nitria the heresy of Origen. We have remembered the warning words of the apostle, rebuke with all authority.Titus 2:15 Therefore on your part, as you hope to receive a share in this reward, you should hasten to bring back with scriptural discourses those who have been deceived. It is our desire, if possible, to guard in our days not only the Catholicfaith and the rules of the church, but the people committed to our charge, and to give a quietus to all strange doctrines.